This report in the Guardian absolutely floored me.
If you have a friend on Facebook who has used the iPhone app version to access the site, then it’s very possible that your private phone numbers – and those of lots of your and their friends – are on the site.
The reason: Facebook’s “Contact Sync” feature, which synchronises your friends’ Facebook profile pictures with the contacts in your phone.
Log in to Facebook to see your phone book. You can get to the phonebook from your profile page by clicking on the “Friends” icon in the upper left corner, then selecting “See All.” There will be a “Phonebook” item in the menu on the upper left side.
I looked through my Facebook phone book; there were no phone numbers from my Android (read Google) contact list, but there were phone numbers from lots of my “Facebook friends.” (This may be because I do not use a Facebook app on my phone; I use the Opera Mini browser to visit Facebook from my phone).
Now, most of my Facebook friends are persons I’ve never met in person and don’t expect to ever meet in person and certainly don’t expect to call on the telephone.
The great majority are politically active persons or geeks; the remainder are family members, real-life friends, all interspersed with a few interesting folks I’m met in the nooks and crannies of the innertubes.
I don’t want their phone numbers and I question whether they want me to have them. Anyone whose phone number I want, I can get directly from that person. That’s what email is for.
Facebook offers the option of turning it off.
I did–er, I tried to. The link crashes with a “Please try again later.”
I am this far from deleting all my content and quitting Facebook. If I didn’t use it to push my personal blog, I likely would have quit it long ago.
I was able to turn off the feature (I use the term loosely) for my account, but the phone numbers from lots of other folks, apparently posted from their accounts, are still there.